MPS Type I (Hurler's Syndrome)

MPS Type I - Mucopolysaccharidosis type I (MPS I), is a genetic disorder that results in the buildup of glycosaminoglycans (GAGs) due to a deficiency of alpha-L iduronidase (IDUA), an enzyme responsible for the degradation of GAGs in lysosomes.[i] Without this enzyme, a buildup of heparan sulfate and dermatan sulfate occurs in the body, precipitating a cascade of debilitating abnormalities.[ii]

MPS I is delineated into three disease phenotypes based on clinical presentation: MPS I-H (Hurler syndrome, severe phenotype), MPS I-H/S (Hurler-Scheie syndrome, intermediate phenotype) and MPS I-S (Scheie syndrome, attenuated phenotype).[iii]

The more severe Hurler phenotype is characterized by impaired cognitive development, progressive coarsening of facial features, hepatosplenomegaly, respiratory failure, cardiac valvulopathy, recurrent otitis media, corneal clouding, musculoskeletal manifestations such as joint stiffness and contractures, and dysostosis multiplex. The symptoms arise after birth and progress rapidly. Most of the patients with Hurler Syndrome phenotype who are not submitted to a specific treatment, progress to death, on average, before the age of 10 years, and is due to complications related to brain damage or cardiorespiratory problems.[iv]

MPS I is a great technical fit for ISP™ because enzyme replacement therapy (ERT) only partially addresses patient needs by slowing the progression of the disease. HSCTs have a relatively high risk of rejection or in the case of ex vivo transduced HSCTs, dangerous downstream differentiation effects, and direct inject gene therapy approaches have either been unsuccessful or thought to be too risky from a regulatory perspective.  MPS I requires treatment for life.  ISP™ based treatments are expected to result in a population of long-lived plasma cells, taking up survival niches in bone marrow, resulting in long-term enzyme production.

From a regulatory perspective, ISP™ therapy strikes a balance between the benefits of a HSCT, and risk profile of ERT.  Despite the risks of HSCT mentioned above, HSCT has the ability to halt progression of the neurological deficit, and prevent premature death due to heart or liver disease. Even when performed early, HSCT will not correct musculoskeletal abnormalities, and the engrafted cells won’t last indefinitely.  An ISP™-based treatment for MPS I is less risky because it uses the patient’s own cells, doesn’t require myeloablative chemotherapy, and can be turned off once administered.  Production of IDUA enzyme from ISP™-modified cells is consistent and more natural than ERT.

Immusoft is currently filing regulatory documentation to support a Phase Ia/Ib clinical trial to treat MPS I with an ISP™ cell therapy product.

[i] James, William D.; Berger, Timothy G.; et al. (2006). Andrews' Diseases of the Skin: clinical Dermatology. Saunders Elsevier. ISBN 0-7216-2921-0 p544

[ii] Neufeld, E. F. (1991). Lysosomal storage diseases. Annu. Rev. Biochem. 60: 257 – 280.

[iii] de Ru M, Boelens J, Das A, Jones S, van der Lee J, Mahlaoui N, Mengel E, Offringa M, O’Meara A, Parini R, Rovelli A, Sykora K-W, Valayannopoulos V, Vellodi A, Wynn R, Wijburg F. Enzyme replacement therapy and/or hematopoietic stem cell transplantation at diagnosis in patients with mucopolysaccharidosis type I: results of a European consensus procedure. Orphanet Journal of Rare Diseases 2011;6(1):55.

[iv] Giugliani R, Federhen A, Rojas MV, Vieira T, Artigalás O, Pinto LL, Azevedo AC, Acosta A, Bonfim C, Lourenço CM, Kim CA, Horovitz D, Bonfim D, Norato D, Marinho D, Palhares D, Santos ES, Ribeiro E, Valadares E, Guarany F, de Lucca GR, Pimentel H, de Souza IN, Correa J Neto, Fraga JC, Goes JE, Cabral JM, Simionato J, Llerena J Jr, Jardim L, Giuliani L, da Silva LC, Santos ML, Moreira MA, Kerstenetzky M, Ribeiro M, Ruas N, Barrios P, Aranda P, Honjo R, Boy R, Costa R, Souza C, Alcantara FF, Avilla SG, Fagondes S, Martins AM. Mucopolysaccharidosis I, II, and VI: Brief review and guidelines for treatment. Genet Mol Biol. 2010 Oct;33(4):589-604. Epub 2010 Dec 1. PubMed PMID: 21637564; PubMed Central PMCID: PMC3036139.

Hemophilia A (Factor VIII Deficiency)

Hemophilia A and hemophilia B are X-linked, genetic disorders that are caused by defective or deficient coagulation factor VIII and IX, respectively, resulting in the inability to form blood clots and sustained bleeding after trauma or injury. Recombinant clotting factor protein is currently used to treat hemophilia at a high cost per patient.  As a therapeutic approach for hemophilia, gene transfer has the potential to provide more consistent levels of circulating clotting factor over an extended period of time for more cost-effective treatment.  Moreover, only modest levels of FVIII or FIX expression (2%-5% of normal) can improve clinical outcomes. We are using the Sleeping Beauty (SB) transposon system to engineer autologous human B cells for secretion of clotting factors as a cellular therapy for hemophilia.  An in vitro system for expansion and differentiation of memory B cells into plasma cells has been developed.  Plasma cells are suitable for sustained delivery of FVIII or FIX, since they secrete high levels of protein and may survive for years in vivo.  For human FIX expression, we assembled an SB transposon with the human FIX coding sequence (codon-optimized with R338L mutation for enhanced potency) regulated by the CAGS promoter.  Elevated levels of hFIX in cultures of B lymphoblastoid cells required co-electroporation of the hFIX transposon along with an SB transposase encoding plasmid, demonstrating the role of transposition in achieving extended hFIX expression. 

There have been remarkable advances recently in the treatment of hemophilia B by systemic AAV8-hFIX administration, but similar treatment of hemophilia A presents a significant challenge due to the size of the FVIII-encoding sequence and the complexity of the protein. We previously demonstrated B-domain deleted hFVIII expression and correction of clotting dysfunction in FVIII deficient mice by hydrodynamic delivery using the SB transposon system (Ohlfest et al, Blood 105: 2691, 2005). Current studies are focused on identifying conditions for effective hFVIII transposon delivery and long term expression in primary human B cells after Sleeping Beauty-mediated transposition. Results from these studies will be applicable to the development of a clinical protocol for treatment of human hemophilia by infusion of B cells genetically engineered using the Sleeping Beauty transposon system.

Reference: Delivery of Human Clotting Factors by Expression from B lymphocytes Genetically Engineered Using the Sleeping Beauty Transposon System

Authors: Kendra A. Hyland, Erik R. Olson, Eric Herbig, Mei Xu, Rian de Laat, and R. Scott McIvor

LCAT Deficiency (Fish Eye Disease)

LCAT is an important enzyme in cholesterol metabolism by virtue of its ability to anchor cholesterol to the lipophilic cores of HDL and low-density lipoprotein (LDL) molecules. It also plays a role in reverse cholesterol transport, the mechanism by which excess cholesterol is removed from cells by HDL and delivered to the liver for excretion.[i][ii]

LCAT deficiency is very rare, the prevalence is below 1/1,000,000, so only sporadic cases have been reported. In both FLD and FED, plasma HDL levels are < 10% of normal levels. Both syndromes also manifest the characteristic presence of corneal opacities due to cholesterol deposits. These deposits begin to form in childhood, affecting the peripheral cornea before reaching the center. In some cases this opacity may necessitate a corneal transplant. Patients with the more severe FLD may also manifest hypertriglyceridemia, normochromic hemolytic anemia, and proteinuria. LCAT deficiency is also thought to enhance atherosclerosis, by interfering with the reverse cholesterol transport. Ultimately the abnormal deposition of lipoprotein in the kidneys due to LCAT deficiency results in end-stage renal disease often in the fourth decade of life.[i][iii]

The normal plasma concentration of LCAT is about 6 μg/mL and varies little in adult humans with age, gender, and lifestyle. The half-life of LCAT in plasma has been estimated to be 4–5 days.[iv] Several studies have demonstrated an inverse correlation between plasma high-density lipoprotein (HDL) and the risk of coronary artery disease, and have concluded that HDL is a powerful predictor of the disease.[iii]

Due to LCAT’s natural enzymatic activity being localized to the vasculature, short half-life of LCAT in serum, and dosage range, LCAT deficiency is a great technical fit for ISP™ delivery.

[i] Stoekenbroek RM, van den Bergh Weerman M a, Hovingh GK, Potter van Loon BJ, Siegert CEH, Holleboom a G. Familial LCAT deficiency: from renal replacement to enzyme replacement. [Internet]. Neth. J. Med. 2013 Jan;71(1):29–31.

[ii] Rousset X, Vaisman B, Amar M, Sethi AA, Remaley ATTT. Lecithin: cholesterol acyltransferase – from biochemistry to role in cardiovascular disease [Internet]. Curr. Opin. Endocrinol. Diabetes Obes. 2009 Apr;16(2):163–171

[iii] Savel J, Lafitte M, Pucheu Y, Pradeau V, Tabarin A, Couffinhal T. Very low levels of HDL cholesterol and atherosclerosis, a variable relationship--a review of LCAT deficiency. [Internet]. Vasc. Health Risk Manag. 2012 Jan;8:357–61.

[iv] Kunnen S, Van Eck M. Lecithin:cholesterol acyltransferase: old friend or foe in atherosclerosis? J. Lipid Res. 2012 Sep;53(9):1783–99.

Recessive Dystrophic Epidermyolysis Bullosa (RDEB)

Epidermolysis bullosa is a group of genetic conditions that cause the skin to be very fragile and to blister easily. Researchers classify dystrophic epidermolysis bullosa into three major types. Although the types differ in severity, their features overlap significantly and they are caused by mutations in the same gene. The autosomal recessive types of dystrophic epidermolysis bullosa (RDEB) result from mutations in both copies of the COL7A1 gene in each cell.

Individuals with moderate and severe forms may have many complications and require psychological support along with attention to the care and protection of the skin and soft tissues. When blisters appear, the objectives of care are to reduce pain or discomfort, prevent excessive loss of body fluid, promote healing, and prevent infection. The doctor may prescribe a mild analgesic to prevent discomfort during changes of dressings (bandages).

Systemic delivery of collagen VII expressing ISP™ cells for the RDEB patient population offers some major advantages over other forms of therapy.  Recent data suggests that intravenously administered C7 could simultaneously migrate to the Dermal-Epidermal Junction (DEJ) throughout the RDEB patient's skin, reverse the “subclinical”, microscopic epidermal-dermal separation and prophylactically prevent frank skin blisters and erosions from forming. We believe that protein therapy via intravenous C7 may be a valid therapeutic strategy for patients with RDEB who currently have few therapeutic options. [i]

[i] Woodley, D. T. et al. Intravenously injected recombinant human type VII collagen homes to skin wounds and restores skin integrity of dystrophic epidermolysis bullosa. J. Invest. Dermatol. 133, 1910–3 (2013).

LPL Deficiency (Type I Hyperlipoproteinemia)

Lipoprotein lipase (LPL) deficiency (a.k.a Type I Hyperlipoproteinemia) is a rare, hereditary disorder of lipoprotein metabolism characterized by severely increased triglyceride levels, and associated with an increased risk for pancreatitis.[i]

Lipoprotein lipase (LPL) is one of the key enzymes in the metabolism of triglyceride-rich lipoproteins (TRLs) and is produced in fat tissue, skeletal muscle and heart muscle.

Activated by its cofactor apolipoprotein (apo) CII,1 LPL mediates the hydrolysis of triglycerides (TG) in chylomicrons (CM) and very-low-density lipoproteins (VLDL) at he luminal side of the endothelium. The generated free fatty acids (FFA) are subsequently used for energy production in muscle tissue or stored as fat in adipose tissue. LPL also contributes to the high-density lipoprotein (HDL) pool by shedding of phospholipids and apolipoproteins during the hydrolysis of these lipoproteins.[ii]

Systemic delivery of LPL enzyme secreted from ISP™ cells for the Type I Hyperlipoproteinemia   patient population offers several advantages over other forms of therapy. 

[i] Gene therapy for genetic lipoprotein lipase deficiency: from promise to practice http://www.njmonline.nl/getpdf.php?id=277

[ii] Taskinen MR, Nikkila EA. High density lipoprotein subfractions in relation to lipoprotein lipase activity of tissues in man—evidence for reciprocal

regulation of HDL2 and HDL3 levels by lipoprotein lipase. Clin Chim

Acta 1981;112(3):325-32.

Sacropenia (Muscle Loss with Aging)

One of the most distinctive characteristics of older people is the presence of skeletal muscle weakness and atrophy. The term sarcopenia was used for the first time by Rosenberg to refer to the loss of lean body mass with aging. The prevalence of sarcopenia in the older population may range from 4% to 27% depending on the gender of the participants and country.

Immusoft has identified a suitable molecular candidate delivered by ISP™ cells to reverse the effects of age-related sacropenia.

HIV

There exists a growing interest in interventions that either fully eradicate all replication-competent HIV (a “sterilizing” cure) or efforts that result in sustained control of persistent virus (often referred to as a “functional cure”). Our overall vision is to target the viral reservoir using gene-modified autologous plasmablasts , which secrete a known broadly neutralizing antibodies isolated from elite HIV suppressors. These antibodies will (1) enable the clearance of rare reservoir cells that spontaneously reactivate (during ART) leading to a gradual but eventually profound decrease in reservoir size and (2) prevent replication of any residual virus after ART is discontinued. 

Immusoft has identified several broadly neutralizing antibodies to be delivered using an ISP™ cell therapy as a cell-based treatment option to prevent or even eradicate an HIV infection.